Shoe stiffener



Patented Nov. 13, 1934 v 1,980,810 snoE STIFFENER Stanley P. Lovell, Newton, Mass., assignor to Arden Box Toe Company, Watertown, Mass., a corporation ot Massachusetts Application June 25, 1932, Serial No. 619,296

11 claims. (o1. 154-46) The subject of this invention is shoe stiffener parts, and more especially those known as box toes and intended to maintain the shape, as well 'as to impart such qualities as strength, resilience, l and water resistance to the fore part of a shoe.

In realizing a box toe of the desired strength and resilience and yet possessed of the proper thinness, it is sometimes the practice to build up a laminated structure Whose plies consist of suitable fabric, e. g., textile fabric or paper felt carrying a suitable stiffening agent. For instance, the plies may carry a coating of celluloid or other cellulose ester capable of being gelatinized by a suitable solvent, so as to permit the stiffener l5 blank to acquire the plastic or mouldable state requisite for incorporation into and shaping with the shoe upper during the pulling-over and lasting operations. When such a stiffener undergoes solvent treatment, the cellulose ester in the coating tends to migrate into the fabric andto lose itself, so to speak, in the fabric fibers, with a consequent loss in stiffness. Under the stress of lasting, this tendency is increased; and the gelatinized cellulose is apt to ooze at the edges of the superposed stiffener plies.

In accordance with the present invention, I construct a, laminated stiifener comprising a fabric ply charged with a suitable stiffening agent and united to a preformed, substantially continuous film of suitable cellulose ester. The fabric ply may be paper felt, woven textile fabric, or the like. The stffening agentA in the fabric may be a compound similar to or dierent from the compound constituting the preformed film, but

it should be capable of being gelatinized by a solvent of the preformed film of cellulose ester. The preferred form of stiffener is one made up of at least three superposed,united plies, the inner ply of which is the preformed film of cellulose ester, and

the outer plies of which are fabric charged with the appropriate stiffening agent. Such a stiffener has the qualities of stiffness and resiliency to a high degree, by virtue of the fact that when it is exposed to solvent action preparatory to assembly with a shoe upper, as by momentary immersion in a solvent bath, the preformed lm is not rendered entirely uid and the stiffener as a whole imbibes comparatively little solvent and hence exhibits a high ratio of stiffening solids to solvent. In other words, the preformed film,

rather than being dissolved and dissipated, merely undergoes incipient solution on its surfaces, wherefore it simply becomes tenaciously integrated with the fabric plies Whose stiffening agent has undergone more or less complete gelatinization by solvent action. The preformed film thus exists in the moulded and assembled stiifener in a condition to augment most effectively the stiffness and resiliency furnished by the stiifened fabric plies. In making the stiffener, I may die 00 out blanks of the proper shape from the preformed film and from the stiffened fabric, and unite them in superposed relationship under the influence of solvent action. For instance, assuming that a fabric has been stiffened by impregnation with a solution of cellulose ester, stiffener blanks may be died out from the fabric while it is still sufficiently wet with the solution to permit bonding with similar blanks cut from the preformed film. Should the impregnated fabric be dried before cutting into blanks, the blanks may be moistened with solvent on their surfaces to be bonded with the blanks of preformed film. Or, if desired, whole sheets of impregnated fabric may be bonded face to face with whole sheets of preformed film, and the resulting laminated structure then died out into shoe stiifener blanks.

In making a three-ply stiener, for example, it

is possible to feed a sheet of the preformed film in between two sheets of freshly impregnated 30 fabric proceeding from the impregnating baths in a properly squeezed condition. The three-ply structure may be fed into press rolls to ensure the desired union between the plies, then dried, and cut into the stiffener blanks.

On vthe accompanying drawing,

Figure 1 illustrates a two-ply stiffener embodyl ing the present invention and whose fabric ply is lifted from the preformed, substantially continuous film.

Figure 2 similarly illustrates a three-ply stiffener.

Figure 3 depicts a stiffener made up with a still larger number of plies and whose thickness is shown greatly enlarged.

The stiffener shown in Figure 1 is a box to and consists of a preformed, substantially continuous film of cellulose ester bonded to a fabric ply charged with a stiifening agent capable of being gelatinized by a solvent of the particular cellulose ester constituting the film. In fact, the stiffening agent for the fabric may be a cellulose ester similar to that of the f'llm. It is preferable, however, that two stiffened fabric plies be combined with an internal stiffening phase of preformed film. y A box toe is shown so constructed, in Figure 2, with cellulose acetate as the stiffening agent in both the film and fabric plies. When more than three plies are used, as in the stiffener illustrated in Figure 3, the stiiened fabric inner 11( plies may well be of the nature of paper felt, and the stiifened outer fabric plies be a Woven or similar textile fabric. The outer plies may be of the same size, whereas the internal laminae may consist of alternate blanks of stiffened paper and preformed film progressively decreasing in size from one outer ply to the other. This means that the stiffener will terminate, as shown, in comparatively thin beveled edges or margins, which comport with comfort and smoothness in the finished shoe. A similar effect may be had by skiving a stiffener, all of whose constituent plies are of the same size, at its marginal or edge portions.

It is inevitable that the amount of stiffening agent per unit of volume is lower in the fabric plies than in the preformed film, as the stiffening agent merely occupies pores and interstices in the fabric, whereas the lm consists entirely of stiffening agent. I prefer that the stiifened fabric have a porosity permissive of a quick penetration of the solvent therethrough, so as to reach the film of cellulose ester, even though this means that the fabric will not be charged with a saturating amount of stiffening agent and thus be stiiienedY short of its potential limit. Let us consider, for example, a three-ply stiiener made in accordance with the present invention and intended to be used in womens street shoes. Such a stiffener may comprise outer fabric plies, such as napped cotton twill, of a thickness of approximately .018 inch and carrying as an impregnant, say, 21/2 to 3 ounces of cellulose ester per square yard, and an inner, preformed lm of cellulose ester of a thickness of only .003 inch and weighing as much as the upper limit of cellulose ester content inthe fabric, namely, 3 ounces per square yard. When the cellulose ester is distributed in only such amount substantially uniformly throughout the fabric plies, they are penetrable substantially instantaneously by a solvent. It is,

of course, to be understood that the foregoing stiiener is one cited by way of illustration only, and that I may introduce into various kinds of fabric plies more or less cellulose ester, depending upon the particular class of shoes into which the stiifen'er is to gc. In any event, however, the stiffened fabric plies are preferably sufliciently porous to permit the penetration thereinto and therethrough ofthe solvent in a reasonable period of time, so as to -wet substantially all of the surfaces of the preformed cellulose ester film.

As an example of one special sphere of utility of my invention, I wish to observe that a box toe made up with an adequate number of plies, as hereinbefore described, is highly advantageous in so-called'safety shoes. A shoe containing such a box toe hasA a fore part not only prooi against water, perspiration, oil, and other liquids, and high in its dielectric properties, but greatly resistant to heavy shock or impact, and so fits nicely into such hazardous occupations as mining, steelmaking, metal pouring, and the like. -In these latter connections, I prefer to use cellulose acetate in both the film and as the impregnant for the fabric plies. The cellulose acetate makes for low infiammability in the stiffener as a whole, wherefore, should the shoe fore part come into contact with fire, molten metal, or other heated objects, the wearers toes are protected against severe burning. I have already adverted to the fact that a shoe stiffener may be constructed, in accordance with my invention, to withstand heavy shock or impact. For instance, a box toe made with seven plies of stiiened fabric and six plies of film, as illustrated in Figure 3, is s tough and resilient as to withstand, without fracture. pressures of at least about 2500 poundsper square inch. This indicates that a shoe into which such a blank is incorporated offers much resistance at its fore part against heavy impact, and hence minimizes injury tol the toes of a wearer when heavy masses accidentally fall upon the fore part.

In some instances, the lm may consist of nitrocellulose and the outer fabric plies contain cellulose acetate as the stifening impregnant. In such case, the solvent used for conditioning the blank as a whole for shoemaking should, of course, be one functioning as a solvent or plasticizing agent 'for both vcellulose acetate and nitrocellulose. There are various solvents or solvent mixtures for both these cellulose esters, e. g., acetone, diacetone-alcohol, diethylene glycol acetate, glycol monoacetate, ethylene oxide; and it is not necessary that the solvent or solvent mixture have the same action on both esters.` The inilammability of such a shoe stifiener is cut down by the outer plies, which serve to shield the highly combustible nitrocellulose lm from direct exposure to heat. Rather than being a cellulose ester, the stiffening agent for the fabric plies may be a compound of another class, capable of undergoing gelatinization by the same solvent designed to act. upon the cellulose ester film. For example, I may use an artificial resin,

e. g., bakelite varnish, as the stiifening agent for the fabric plies. In such case, the solvent selected for conditioning the stifener as a Whole for shoemaking is one common to both the artificial resin and the cellulose ester film. By using in the fabric plies a stiffening agent whose character is quite different from' a cellulose ester, it is possible to realize a combination of characteristics in the composite shoe stiffener unattainable by the use of a single stiifening agent, such as cellulose acetate or nitrocellulose. Thus, the stiifener may comprise fabric plies impregnated with a suitable resin, such as cumar resin, which is characterized by its extreme hardness and stiffness under normal temperature conditions, but which has the fault of being easily shattered by impact. This. fault of easy shatterability in the cumar resin carried. by the fabric plies may be so offset by the flexibility and resiliency of the cellulose ester lm that the stiifener as a unit is characterized by the desirable increase in hardness and stiffness afforded by the cumar resin, while at the same time being adequately resilient and flexible to meet all the needs in service.

It is preferable that the outer fabric plies in the stiifeners of the present invention be woven or similar textile fabric, so as to contribute mecha-nical strength to the stiifener. In the case of box toes, such fabric plies are desirable, because the stiffeners undergo considerable pulling stress as they are being formed to the shape of the last. When, however, such a stiiener contains more than three plies, only the outer plies need be made of woven or similar textile fabric. The rest of the fabric plies may be paper felt or similar inexpensive fibrous foundation.

Rather than being stiffened by impregnation with a solution of the stiffening agent, the paper felt and/or the woven or other textile fabric plies may be charged with comminuted or powdered stiifening agent.. In such instance, high porosity is necessarily a concomitant quality of the stiffened fabric plies. In the case of a paper felt, the cellulose ester or other stiffening agent may be introduced as a powder, precipitate, aqueous dispersion, or in any other suitably subdivided state into the papermaking pulp in the beater engine before the pulp is formed into a web on the papermaking machine. In the case of a textile fabric, the powdered cellulose ester or other finely divided form of stifening agent may be forced into the pores and interstices of the fabric in the condition of an aqueous or other suitable paste, by squeeze rolls or their equivalent. f

I claim:

l. A laminated shoe stiiener, comprising at least three plies bonded together in superposed, face-to-face relationship, the inner ply consisting of a preformed, substantially continuous film of cellulose ester and the outer plies consisting of fabric charged with stiflening agent coming from a source other than said film and capable of being gelatinized by a solvent of said cellulose ester.

2. A laminated shoe stiffener, comprising at least three plies bonded together in superposed, face-to-face relationship, the. inner ply consisting of a preformed, substantially continuous film of cellulose acetate and the outer plies consisting of fabric charged with cellulose acetate coming from a source other than said film.

3. A laminated shoe stiflfener, comprising a preformed, substantially continuous film of cellulose ester bonded face to face with a fabric impregnated with a stiffening compound other than said cellulose ester but soluble in a solvent of said ester.

4. A laminated shoe stiffener, comprising a preformed, substantially continuous lm of nitrocellulose bonded face to face with a fabric impregnated with cellulose acetate.

5. A laminated shoe stiffener, comprising a preformed, substantially continuous fllm of ce1- lulose ester bonded face to face with a fabric impregnated with a stiffening compound other than a cellulose ester but gelatinizable in a solvent of the ester of said film.

6. A laminated shoe stiffener, comprising a plurality of preformed, substantially continuous films of cellulose ester, bonded face to face in alternating relationship with fabric plies charged with a stiifening agent coming from a source other than said films and capable of being gelatinized by a solvent of said cellulose ester, said stiffener containing stiffened woven textile fabric as the outer fabric pliesl and stiffened paper felt as the inner fabric plies.

7. A laminated shoe stiffener especially adapted for use in safety shoes, comprising a plurality of preformed, substantially continuous films of cellulose acetate bonded face to face in alternating relationship with fabric plie's charged with cellulose acetate coming from a. source other than said-films, said stiffener containing as the outer plies woven textile fabric chargedk with the cellulose acetate.

8. A laminated shoe stiffener, comprising a preformed film of cellulose ester bonded face to face with a fabric charged substantially throughout with stiffening agent in subdivided form and capable of being gelatinized by a solvent of said cellulose ester.

9. A laminated shoe stiffener, comprising a preformed film of cellulose acetate bonded face to face with a fabric charged substantially throughout with cellulose acetate in subdivided form and capable of being penetrated quickly by a cellulose acetate solvent.

10. A laminated shoe stiffener, comprising at least three plies bonded together in superpos'ed, face-to-face relationship, the inner ply consisting of a preformed film of cellulose ester and the outer plies consisting of fabric charged substantially throughout with cellulose ester in subdivided form and capable of being penetrated quickly by a cellulose ester solvent.

l1. A laminated shoe stiffener, comprising at least three plies bonded together in superposed,

face-to-face relationship, the inner ply consist- I ing of a preformed film of cellulose acetate and the outer plies consisting of fabric charged substantially throughout with cellulose acetate in subdivided form and capable of being penetrated quickly by a cellulose acetate solvent.

STANLEY P. LOVELL. 

